The present invention relates to injection molding machinery and more specifically to temperature control systems for use in an injection molding machine.
A typical injection molding machine includes a feed assembly having a barrel down which plastic materials are fed into a mold. The plastic materials are fed into the barrel in a solid granular state and are melted within the barrel for injection into the mold in a liquid state. The control of the temperature within the feed assembly is critical to the operation of the machine, and it is important that when the machine is started up from cold conditions, it is accurately and rapidly brought up to its set point temperature without significant overshoot. Additionally, it is a great benefit to identify parameters for use in the steady state control at the time of start up so that steady state control functions can be autotuned in accordance with operating conditions.
It is therefore an object of the present invention to provide a control system for use in controlling the temperature of the barrel in the feed assembly of an injection molding machine which has the capability of rapidly and accurately bringing up the barrel temperature to the command temperature under cold start up conditions.
It is another object of the present invention to provide a control system which enables rapid startup of injection molding machinery from cold conditions and which also provides autotuning of control parameters for use under steady state conditions during the cold startup procedure.
It is a further object of the present invention to provide a control program for execution by a programmable controller which allows for rapid and accurate cold startup of temperature machinery and sensitive identification of the control parameters for use under later steady state conditions during the cold start up procedure.